1. Field of the Invention
The present invention relates to a method for packing a solid organometallic compound into a container for packing and also relates to a solid organometallic compound-packed container packed by means of the packing method. More particularly, the invention relates to a method for packing a solid organometallic compound into a container for packing, wherein the solid organometallic compound can be stably supplied to a vapor phase epitaxial growth apparatus at a constant concentration for a long period of time. A solid organometallic compound serves as a material for vapor phase epitaxial growth by means of, for example, a Metalorganic Chemical Vapor Deposition (hereinafter, abbreviated as “MOCVD”) method which is employed when a material for electronics industry such as a compound semiconductor is manufactured. Also, the invention relates to a solid organometallic compound-packed container packed by means of the packing method.
2. Description of the Related Art
An organometallic compound such as trimethylindium has widely been used as a raw material for manufacturing a material for electronics industry.
Recently, vapor phase epitaxial growth by means of the MOCVD method or a similar method has often been used as a manufacturing method of a material for electronics industry by use of an organometallic compound. For example, a thin film of a compound semiconductor has been manufactured by means of the MOCVD method. In this case, an organometallic compound such as trimethylaluminum, trimethylgallium, or trimethylindium has been employed as a raw material.
In the MOCVD method in which such an organometallic compound is employed, if the organometallic compound is solid under the use conditions thereof, the organometallic compound is normally supplied to an MOCVD apparatus by means of the following method. That is, the organometallic compound is packed into a container for packing (hereinafter referred to as a packing container A) including a carrier gas inlet (2a) and a carrier gas outlet (3a) shown in FIG. 33. A carrier gas such as hydrogen gas is introduced into the container from the carrier gas inlet (2a), and then the carrier gas saturated with the organometallic compound is drawn from the carrier gas outlet (3a) and supplied to the MOCVD apparatus.
In this case, if the organometallic compound is solid at an operating temperature of the above supplying method, a certain flow path may be formed in which the carrier gas passes through the packing container A without sufficiently contacting with the solid organometallic compound. For this and other reasons, it is difficult to maintain a uniform contact state between the carrier gas and the solid organometallic compound. Thus, a problem arises that the solid organometallic compound is not stably supplied by the carrier gas from the packing container A to the MOCVD apparatus at a constant concentration for a long period of time. In addition, in the abovementioned method for supplying the solid organometallic compound by use of the carrier gas, as the amount of the compound packed into the packing container A increases, the ratio of the amount of the compound which can be stably supplied to the MOCVD apparatus to the above packed amount decreases. Therefore, a problem arises that the solid organometallic compound cannot be efficiently used since the unused amount of the compound increases in the packed container.
In order to solve the above problems, various methods have been proposed for packing a solid organometallic compound into the packing container A. For example, a method has been proposed in which a solid organometallic compound is packed into a packing container together with a packing material (see, for example, Patent Documents 1 to 5 listed below). Also, for example, a method has been proposed in which an inert carrier is coated with a solid organometallic compound and is packed into the packing container A (see, for example, Patent Document 6).
In addition, in a method for solving the above problems, various structures of a packing container itself have been proposed for packing a solid organometallic compound. For example, a structure of a packing container has been proposed which has a diffuser (20a) provided in a carrier gas inlet for uniformly distributing gas, as shown in FIG. 34 (see, for example, Patent Document 7). In this container (hereinafter referred to as a packing container B), a carrier gas is allowed to uniformly flow through a solid organometallic compound.
Also, a packing container (hereinafter referred to as a packing container C) has been proposed which has a solid organometallic compound chamber (21a) having air permeability, as shown in FIG. 35 (see, for example, Patent Document 8).
Moreover, a packing container (hereinafter referred to as a packing container D) has been proposed in which a porous inlet chamber serves as a packing portion for a solid organometallic compound, as shown in FIG. 36 (see, for example, Patent Document 9).
In addition, a method has been proposed for controlling grain size to stably supply a solid organometallic compound in the case where a ruthenium compound is employed (see, for example, Patent Document 10).    [Patent Document 1] Japanese Patent Publication No. Hei 5-39915    [Patent Document 2] Japanese Patent Publication No. Hei 6-20051    [Patent Document 3] Japanese Patent Laid-Open Publication No. Hei 7-58023    [Patent Document 4] Japanese Patent Laid-Open Publication No. Hei 8-250440    [Patent Document 5] Japanese Patent Laid-Open Publication No. Hei 8-299778    [Patent Document 6] Publication of Japanese Patent No. 2651530    [Patent Document 7] Japanese Patent Publication No. Hei 2-124796    [Patent Document 8] Japanese Patent Laid-Open Publication No. Hei 10-223540    [Patent Document 9] Japanese Patent Laid-Open Publication No. 2002-83777    [Patent Document 10] Japanese Patent Laid-Open Publication No. 2003-160865
However, in the packing methods and the packing containers proposed in Patent Documents 1 to 9, studies have not been made for the grain size of a solid organometallic compound itself to be packed into the packing container.
Also, in Patent Document 10 or the like, the effect of controlling the grain size of the ruthenium compound on the supply stability is described only for an initial supply state. This consideration has been made by producing films only several times, and it is not clear that the effect is maintained to stably supply the ruthenium compound at a constant concentration for a long period of time. The present inventors have conducted studies and found that a grain size-controlling method exists for obtaining not only initial stability but also long-term stability upon supplying a solid organometallic compound by use of a carrier gas.